Observability

Pass --qlog <dir> to either side to emit xquic qlog. Per-path byte counts confirm that within-stream multipath is actually splitting a flow across paths — the key signal that aggregation is working.

Metrics

• --metrics-interval <sec> periodically logs per-path stats as mq.conn / mq.path logfmt lines. On the server it logs the most-recently-accepted TCP and gateway connection; on the client it logs the proxy connection (and the gateway connection when --gateway is set).
• With --mitm, the client also logs a mq.mitm line on every tick and at shutdown: live MITM connections and streams, how many connections were terminated versus relayed opaquely (per reason), TLS/h2 failures, leaf-certificate cache hits and misses, and request counts. See the TLS MITM guide for every field.
• --request-metrics (server, gateway) emits one mq.req logfmt line per gateway request (method/status/target/ttfb/origin_protocol/cache/…). Opt-in and independent of --metrics-interval.

Testing

Run the test suite from the repository root:

cargo test --workspace --locked
cargo clippy --workspace --all-targets --locked -- -D warnings
cargo build --release --locked -p mqproxy --bins --examples
bash tests/test_cli_help.sh target/release/mqproxy
bash tests/integration/e2e_udp.sh     # also e2e_{gateway,multipath,tproxy,mitm_h2,...}.sh

The cargo tests cover wire framing, the relay/flow state machine, ingress parsing, the gateway request path, and TLS MITM. The tests/integration/e2e_*.sh scripts run end to end: multipath aggregation, the full gateway chain, UDP relay, transparent capture and MITM. Scripts that need root or NET_ADMIN skip themselves when run unprivileged.